Film-forming resins have been added to hair dressing composition such as hair spray and set lotion in order to impart various effects including setting and set-retention to these products. Examples of commonly employed film-forming resins include polyvinyl pyrrolidone, polyvinyl pyrrolidone/vinyl acetate copolymer and vinyl acetate/crotonic acid copolymer.
A film-forming resin conventionally contained in a hair dressing composition would show a certain degree of set-retention under commonly employed conditions. Under highly humid condition, however, the adhesiveness and fluidity thereof would be increased by moisture absorption, which makes it impossible to effectively retain a hair set. On the other hand, a hair dressing composition should be readily washed away with the use of a shampoo. That is to say, a film-forming resin to be added to a hair dressing composition should have a high solubility in water as well as a low hygroscopicity. It is difficult to simultaneously satisfy these conflicting requirements. Thus it is frequently observed to give up to achieve a high solubility of a film-forming resin in water and employ other solvent or a mixture of solvents.
Freon gas, which has been widely used as a propellants hitherto in various aerosol compositions, is an ideal propellants from the viewpoints of chemical stability, combustibility and toxicity. Recently, however it has been pointed out that Freon gas might cause an environmental problem, namely, the breakage of the ozone layer. Therefore a tendency to replace Freon gas with incompletely halogenated ones or propellants free from any halogen atom is seen lately. Examples of such propellants include hydrocarbons (LPG) such as propane, butane, isobutane and mixtures thereof. However a film-forming resin generally shows a lower solubility in LPG than in Freon gas. When the propellant in a conventional aerosol composition is simply replaced with LPG, therefore, the film-forming resin in the aerosol composition would be precipitated and thus the product cannot be used any longer. Accordingly it is required to use a larger amount of a solvent such as ethanol or isopropyl alcohol in a spray in order to fully dissolve the film-forming resin in the LPG. When sprayed, the hair dressing composition product thus obtained forms a thick and heavy mist, which makes it difficult to give a beautiful hair set.
Furthermore, some setting products such as hair spray make the hair coarse or rough after drying.
Further there are some additional problems such that the resin film thus formed on the surface of the hair peels off when brushed, namely, so-called flaking, and that the gloss of the hair is deteriorated.